code: def test_subclassing_feature():
      class EmptyFeature(dipysfeature.Feature):
          pass
  
      feature = EmptyFeature()
      assert_raises(NotImplementedError, feature.infer_shape, None)
      assert_raises(NotImplementedError, feature.extract, None)
  
file_path: dipy/dipy/segment/tests/test_feature.py
imports: import sys
  import numpy
  from numpy.testing import assert_array_equal, assert_array_almost_equal, assert_raises, assert_equal
  import dipy.segment.featurespeed
  import dipy.segment.metric
  import dipy.segment.metricspeed
  from dipy.segment.featurespeed import extract
  from dipy.testing import assert_true, assert_false
  from dipy.testing.decorators import set_random_number_generator
label_desc: Use image node_id 8 for calling a global function with example usage: test_subclassing_feature() without return types